Antifungal activity of the extracts and neolignans from Piper regnellii (Miq.) C. DC. var. pallescens (C. DC.) Yunck

Piper regnellii (Miq.) C. DC. var. pallescens (C. DC.) Yunck (Piperaceae) is a medicinal plant traditionally used in Brazil to treat infectious diseases. The extracts obtained from the leaves of P. regnellii were investigated for their antifungal activities against the yeasts Candida albicans, C. krusei, C. parapsilosis, and C. tropicalis. The EtOAc extract presented a significant activity against Candida albicans with MIC at 125 μg mL-1, and a moderate activity against both C. krusei and C. parapsilosis with MIC at 500 μg mL-1. Candida tropicalis was not inhibited by this extract at concentrations as high as 1000 μg mL-1. Based on these findings, the EtOAc extract was fractionated by silica gel column chromatography into nine fractions. The hexane and CHCl3 fractions showed varied levels of antifungal activity against all test yeasts. Further column chromatography separation of the hexane fraction afforded the pure compounds eupomatenoid-6, eupomatenoid-5, eupomatenoid-3 and conocarpan. The structure of the compounds was based on spectral data (1H and 13C NMR, HSQC, HMBC, gNOE, IR and MS). Conocarpan was the only active compound on the yeasts. The antifungal property of P. regnellii extract provides preliminary scientific validation for the traditional medicinal use of this plant. (author)